Process of forming phonograph-styli.



T. A. EDISON.

PROCESS 0F FOBMING- PHONOGRAPH STYLI.

APPLIGATION FILED 11.13.23, 1910.

1,1 10,428, Patented sept. 15,1914.

2 SHEETS-SHEET 2.

0 wry/ZW? UNITED STATES `PATENT OFFICE.

THOMAS A. EDISON, OF LLEWELLYN PARK, WEST ORANGE, NEW JERSEY, ASSIGNOBTO NEW JERSEY PATENT COMPANY', OF WEST ORANGE, NEW JERSEY, A CORPO-RATION OF NEW JERSEY'` PROCESS OF FORMING PHONOGRAPH-STYLI.

Application led March 23, 1910. Serial No. 551,128.

To all whom it may concern:

Be it known that I, THOMAS A. EmsoN, a

citizen of the United States, and a resident of Llewellyn Park, WestOrange, Essex county, New Jersey, have invented certain new and usefulImprovements in Processes of Forming Phonograph-Styli, of which thefollowing 1s a description.

My invention relates-to phonograph styll, and more particularly to aprocess of forming reproducing styli of extremely hard material such asdiamond, which styli are capable of operating upon records of very hardmaterials without wearing away or otherwise deteriorating.

My objects are the provision of an 'lm proved process for shaping such astyli, and the production of such a styli as an article of manufacturewhich is adapted to be used in combination with a suitable reproducerwhich is given a considerable weight, sufficient to hold the stylusfirmly in contact with the record surface at all times, and also incombination with a record formed of material of such excessive hardnessas to withstand the wearing action of the stylus and having formedthereon a record groove of fine itch. p

Ot ier objects of my invention will appear from the followingspecification and appended claims.

Diamond has heretofore been mentioned among other materials as suitablefor reproducing styli, but this has been a mere suggestion that in viewof the exceeding hardness of the diamond, it would be of great value asa material from which reproducing Styli might be made. The properconstruction of a diamond stylus or a stylus formed of materialsubstantially harder than sapphire, however, has never been disclosed tomy knowledge, nor has such a st lus ever appeared commercially. I haveound that an exceedingly hard record material such as that disclosed inapplications of Aylsworth, Serial Nos. 496,060, plastic composition andprocess of manufacturing the same, tiled May 14, 1909; 543,238, phenolicoondensation product and method of preparing same, filed February 11,1910; and 543,236, sound records and process for making the same, filedFebruary 11, 1910, wears away the usual sa phire stylus to aconsiderable extent. T e materials described in these applications arefinal condensation products of phenol, its homologues or polymers, andformaldehyde or heXa methylene tetraamine or other substance containingthe methylene radical CH2, and in their final condition are much harderthan Celluloid, and in fact nearly approach glass as to their hardness.Such a record material or one of equivalent or great hardness, harder,for example, than Celluloid, is preferably of the utmost value for theproduction of a molded phonograph record, since with a record formed ofsuch material, a reproducer of considerable weight or provided with aheavy floating weight may be used with a consequent considerableimprovement in the volume and Hciluality of reproduction, if a stylus ofsu cient hardness to withstand the wear caused by the hardness of therecord is used therewith. Furthermore, with a record having anexceedingly fine pitch, it is necessary that the material be very hardin order that the fine walls between the grooves shall not be brokendown in reproduction. appreciably worn when used in reproducing fromsuch records, both disk and cylinder, as are now on the market, of whichthose formed from celluoid are probably the hardest. When, however, therecord material is substantially harder than celluloid, a sapphirestylus quickly wears out, and accordingly, I have constructed a diamondstylus which is ada ted to coact with such a record and to wlthstand theconsequent wear. It should be noted that as a test, over 300reproductions were made under my di- A sapphire -stylus is not rectionwith a reproducer wei hing from 3 to 5 ounces and provided wit a diamondstylus such as I will describe, operatinor upon a record of they typehaving a vertically vundulating groove and formed of a phenolic finalcondensation product, described in the above mentioned applications ofAylsworth, compounded with finely divided wood pulp. This test resultedin no appreciable wear, either of the record surface or of the stylus.

Reference is hereby made to the accompanying drawings forming part ofthis specification, and in which- Fi ure 1 represents in perspective adiamon splint from which my improved stylus is formed. Figs. 2, 3 and 4are similar views of the splint showing the different stages loo ` ingpoint thereon. Fig.

of operation in the shapin of the reproduc- 5 1s a diagrammatic viewshowing the method of lapping the end of the splint to a flatsurfaceUvhich 1s preferably the first step in my. improved process. Fig.6 is a diagrammatic side elevation partly in cross section showing themethod of holding the stylus and lappin or grinding a taper upon the endthereo Figs. 7 and 9 are respectively a partial plan and side elevationof suitable apparatus for performing the final step of my process,consisting 1n roundin the end of the stylus. Fig. 8 is an enlarge crosssection on line 8-8 of Fig. 9 showing a detail of construction. Fig. 10is a partial cross section through a reproducer provided with myimproved diamond stylus traveling in the record groove of a suitablesound record formed of hard material such as described above. Figs. 11and 12 are side elevations of the splint in rough and finished conditionrespectively, entirely inclosed Within a holder of soft metal,illustrating steps in a modification of my process.

Particular suitable mechanism by which my process may be carried outwill be described fdr the sake of clearness. but it is to be understoodthat my process is not limited to such mechanism.

Referrin to the drawings, my improved stylus is ormed from a diamondsplint, such as indicated at 1. Splints such as that illustrated and ofsuitable size may be obtained in the market, or they may be prepared byfirst cleaving a diamond into flat plates and then notchlng these plateswith diamond dust and breaking the same into splints. Such splints areof various shapes and are more or less irregular and rough inappearance. In the formation of a stylus from such a splint, I prepareonly one end of the splint, since the roughness and irregularity of thebody of the splint are really advantageous, since they aid in firmlyholding the s lint in the chuck during the formation o the stylus and inthe stylus lever after the stylus is completed.

Having obtained the splint, I referably first grind the end thereof to aat surface by means of a revolving lap Wheel charged with diamond dust.In Fig. 5 I have illustrated diagrammatically a lap wheel 2 whichrevolves about spindle 3, and being charged With diamond dust upon itssurface 1, grinds the flat surface 5 upon the end of splint 1, asindicated in Fig. 2. During this operation, the splints may be securedin a suitable holder. Having ground the fiat surface 5 upon the end ofthe splint, the next operation is grinding the sides of the splintadjacent to the flat end 5 to a taper, resulting in the production of aconical surface 6 upon the end of the splint, as shown in Fig. 3. Thesplint 1 may be secured in a suitable holder 7 of brass or othersuitable material by cement, which holder is chucked in a lathe such asindicated in Fig. 6, in which the spindle 8 is rotated by means of abeltY passing over Wheel 9, or by other power connection. lVhile thesplint 1 is being rotated, it is ground at a suitable angle, preferablof approximately 30 degrees by means ofy the lap wheel 10, which ischarged With diamond dust and mounted upon shaft 11, which may beadjusted at any suitable angle and rotated by any suitable meansindicated diagrammatically by the belt Wheel 12. If deslred, the twosteps of the process so far described may be transposed, and the sidesof the splint adjacent to the end first ground to a taper and the roughend surface remaining then flattened. Or if the end of the splint issufficiently regular, it may not be necessary to flatten the end at all,and the same may be left rough. After the end portion of the splint hasbeen reduced suliiciently so that the point or flat surface 5 is ofsufficiently small area, the latter is rounded and polished by anysuitable means, such as the ball polishing machine showndiagrammatically in Figs. 7 and 9. As here shown, the splint l securedin a holder such as 7 is chucked in a lathe having a rotating spindlesuch as 8. The end of the splint 1 is rounded and polished by means ofthe grinding tool 13 which is provided with a concave surface of theshape and size to which it is desired to round the end of the splint.

The inding surface of the tool 13 may be chargeY with diamond dust mixedwith oil, as indicated in Fig. 8 at 14. Either the stylus or the toolgrinding the same should partake of an oscillatory movement during therotation of the stylus. In the drawings, I have illustrated the grindingtool 13 as suitably mounted in a spindle 15, which is revolved by meansof elt Wheel 16, the' spindle and belt being mounted in a holder 17,which is pivoted as shown at 18 directl below the end of the stylusbeing round so that during the inding operation, the spindle 15 may oscllate about the surface being ground, as indicated by the positions ofthe spindle 15 shown in dotted lines in Fig. 7. The end of the styluswhen rounded is shown in Fig. 4 at 19, the said figure representin thecompleted stylus. The curve 19 shoul be of the roper dimensions totravel within the excee ingly minute sound record groove, the conicalsurface 6 of the splint preferably running smoothly into the curve 19 ofthe record-engaging surface of the stylus. ing record having 150 threadsto the inch, I have found that a stylus in which the curve 19 has adiameter of .008 inch gives good results.

In the case of a vertically undulat- A modification of the processoutlined above, which I have found valuable, consists in inclosing theentire splint in a holder of brass or other soft material, andsubjecting the splint inclosed in the holder to the same grindingoperations as described above, where the splint Was illustrated asprojecting from the holder. In this method, in grinding the splint theadjacent portions of the holder are also ground away, the holderprotecting the splint against breakage dur ing the operations in thesame manner as the wood of a lead pencil protects the lead in sharpeningthe pencil. This is of value since otherwise the splint is likely to bebroken during grinding. In Fig. 11 I have illustrated tie splint 1entirely inclosed within holder 7 and held therein by cement 7. Thelower end of the holder and splint shown in Fig. 11 is ground fiat, ifnecessary, and the sides of the holder and the inclosed splint ground toa taper and the end of the splint rounded in the holder as shown in Fig.12.

The methods above indicated for shaping styli give them great strengthand seem to be the only practical methods of shaping them Without havingrecourse to a large amount of grinding, which results in a loss ofstrength. A stylus so formed is adapted to track either a disk or acylindrical record. In Fig. 10, I have illustrated a stylus 1 connectedby lever 20, pivoted at 21, to diaphragm 22 of reproducer 23. Thisreproducer is preferably of considerable weight, as, for example, from 3to 5 ounces or more, which weight holds stylus 1 iirmly in engagementwith the record groove of record 24, which is hpreferably formed of theiinal phenolic condensation product above referred to.

Having now described my invention, what. I claim and desire to protecthy Letters Patent is as follows:

1. rIhe process of forming phonograph and incloscd piece to a coneshape, and then F' rounding the point of the piece while still securedin the holder, substantially as described.

2. The process of formingT phonograph Styli and the like which consistsin snbstantial'ly inclosing a small piece ot very hard material within aholder of comparatively soft material, grinding the end of the holderand inelosed piece to a cone shape, and then rounding the point of thepiece by causing relative rotation and oscillation of the holder withthe piece therein and a tool in engagement with said point,substantially as described.

3. The process of forming phonograph styli and the like which consistsin securing a small piece of very hard material in a holder ofcomparatively soft material in such a manner as to substantially inelosethe piece therein, lapping the end of the piece to a Hat end surface,grinding the sides of the piece adjacent said end surface to a coneshape tapering down to the remaining portion of said end surface andthen rounding the said end, substantially as described.

This specification signed and witnessed this llih day of March 1910.

THOMAS A. EDISON.

Witnesses:v

Ptmsnm. EGGnEs'roN, HERMAN WoLlm.

lit)

A -modification of the process outlined above, which I have foundvaluable, consists in inclosing the entire splint in a. holder of brassor'other soft material, and subjecting the splint inclosed in the holderto the same grinding operations as described above, where the splint wasillustrated as projecting from the holder. In this method, in grindingthe splint the adjacent portions of the holder are also ground away, theholder protecting the splint against breakage during the operations inthe same manner as the wood of a lead pencil protects the lead insharpening the pencil. This is of value since otherwise the splint islikely to be broken during grinding. In Fig. 11 I have illustrated thesplint 1 entirely inclosed within holder 7 and held therein by cement 7.The lower end of the holder and splint shown in Fig. 11 is ground flat,if necessary, and the sides of the-holder and the inclosed splint groundto ataper and the end of the splint rounded in the holder as lshown inFig. 12.

The methods above indicated for shaping styli give them great strengthand seem to hev the only practical methods of shaping them withouthaving recourse to a large amountof grinding, which results in a loss ofstrength. A stylus so formed is adapted to track either a disk or acylindrical record.. In Fig. 10, I have illust-rated a stylus 1connected by lever 20, pivoted at 21, to diaphragm 22 of reproducer 23.This reproducer is preferably of considerable y weight, as, for example,from 3 to 5 ounces the final phenolic condensation or more, which weightholds stylus 1 firmly in engagement with the record groove of record 24,which is preferably formed of product above referred to. l

[SEAL] Corrections in4 Let-ters Patent No; 1,1 10,428.

Having now described my invention, wha t I claim and dcsireto protect byLetters Iatcnt is as follows:

1. The process of forming phonograph and inclosed piece. to -a coneshape, and then rounding the point of the piece while still secured inthe holder, substantially as' described.

2. The process lof forming phonograph Styli and the like which consistsin substantially inclosingl a small piece ot very hard material within aholder of comparatively soft material, grinding the end of the holderand inclosed piece to a cone shape, and then rounding the point of thepiece by causing relative rotation and oscillation of the holder withthe piece therein and a tool in engagement with said point,substantially as described. p 3. The process of forming phonograph styliand the like which consists in securing a small piece of very hardmaterial in a holder of comparatively soft material in ysuch a manner asto substantially inclose the piece therein, lapping the end of the pieceto a flat end surface, grinding the sides of the piece adjacent said endsurface to a cone shape tapering down to the rc maining portion of saidend surface and then rounding the said end, substantially as described.

This specilication signed and witnessed this 12F-ih day of March 1910. v

THOMAS A. EDISON.

Witnesses:.

PURSELL EGGLEs'roN, HERMAN WoLKE.

It is hereby certified that in Letters Patent No. 1,110,428, grantedSeptember-15,

1914, upon the application of Thomas A. Edison, of Llewellyn Park, WestOrange, New Jersey, for` anl improvement in Processes of FormingPhonograp'h-Styli, errors appear in the printed speciication requiring'correction as follows: Page 1, lines 17 and 18, for the word stili readstylus; same page, line 64, strike out the Word preferably; page 2, lineft2, before the word formed insert the word prqferaly; and that the saidLetters Patent should be read with these Acorrections therein thatthe'same may conform to the record of the case in the Patent Oiiice.

Signed-and sealed this 6th day of October, A.' D., 1914.

R. F. WHITEHEAD,v

Acting Commissioner qf Paients.

(iii

It is hereby certified that in Letters Patent No. 1,110,428, grantedSeptember 15,

1914, upon the application of Thomas A. Edison, of Llewellyn Park, WestOrange,

New Jersey, for an improvement iu Processes of Forming Phonograph-Styli,

errors appear in the printed specification requiring correction asfollows: Pego 1,

lines 17 and 18, for the word stili read stylus; same page, line 64,strike out the word preferably page 2, line 32, before the word formedinsert the word preferably; and that the said Letters Patent should beread with these corrections therein that the same may conform to therecord of the case in the Patent Ohcc.

Signed and sealed this 6th day of October, A. D., 1914.

[SEAL] R. F. WHITEHEAD,

Acting Commissioner of Paients.

